The present invention relates in general to the design of a replaceable cartridge filter element which is received by an outer housing. More specifically the present invention relates to the design of a replaceable cartridge filter element which includes a seal for sealing the interface between the cartridge filter and the outer housing. The housing-to-element interface at the open (upper) end of the housing is not sealed unless the cartridge filter element is properly installed.
One of the design challenges with any replaceable cartridge filter element is to ensure that the new element will be compatible with the housing which receives the cartridge filter element. It is important to understand the housing design and the locations where fluid leakage can occur. Since there are a wide variety of housing styles as well as cartridge filter elements for various fluids, there are numerous sealing concepts found in the prior art. Even with a fairly routine cartridge filter element design, there is still a wide range of endplate, cover, and housing configurations. Various structural features of these configurations help to seal the element in position and help to cooperatively create the requisite sealing at the interfaces where fluid leakage could occur.
After the cartridge filter element is properly seated and sealed within the housing, the assembly is ready to be attached to or into the engine. With oil filters, the assembly is often connected to the engine block mounting base. Once mounted, the fluid flow path for the oil to be filtered enters the annular space between the element and the housing. The oil passes through the element from the outside and exits by way of the hollow interior. A nutplate may be used in order to provide the inlet flow apertures for the oil entering from the mounting base as well as the centered flow exit.
When the fluid to be filtered is fuel, the mounting and connection to the fuel source is different than what is typically provided for oil filtration. Instead of mounting to an engine block mounting base, the fuel filter is positioned in the engine and fuel inlet and fuel outlet lines are connected to the fuel filter inlet and the fuel filter outlet, respectively. For fuel filters, the housing and lid designs are different from those typically associated with lube filters and those differences will be described herein in the context of the present invention. An important aspect in the design of fluid filters of the type described herein is the elimination of leakage and preventing a bypass of the filter element by the xe2x80x9cdirtyxe2x80x9d fuel.
In this type of filter design, the cartridge filter element is sealed in order to control the fuel flow through the element by way of the desired flow path. The filter design needs to prevent any short cut or short circuit flow paths which would result in the dirty fuel bypassing the filtering media. The present invention addresses this sealing concern in a novel and unobvious manner by the use of a plastic seal retainer which is ultrasonically welded to the plastic endplate of the fuel filter element. The retainer carries an outer, elastomeric seal that seals against the filter housing in cooperation with a closing lid. Also included is a central, generally cylindrical portion that receives an O-ring which is used to seal the top of the cartridge filter element to the lid around the fuel exit aperture.
While the idea of using an outer seal for sealing directly to the housing and lid is believed to be known, the typical approach does not use a separate retainer component (plastic) which is ultrasonically welded to the plastic endcap which in turn is bonded to the filtering media. By welding a special retainer to the endplate, it is easier to selectively add the retainer or not add it, without needing to change the design of the endplate. It is also possible to add the same style of retainer to various styles of endplates. Overall, it should be easier, less complicated, and less expensive to mold the desired endplate separately from the retainer and then mold a xe2x80x9cstandardxe2x80x9d retainer which can be used in combination with a number of different endplate designs.
The present invention also contemplates a uniquely styled upper endplate which includes a shallow inner, annular projection designed to extend only a short distance into the hollow interior of the element. The uniquely styled lower endplate includes a much longer central, generally cylindrical projection. This lower endplate projection extends from the lower end of the element toward the upper endplate and is configured with a spaced series of fuel flow apertures. This unique design of the lower endplate simplifies the manufacturing process for the fuel flow apertures. The outer housing includes a base portion and an integral center tube. The cartridge filter element is positioned over this center tube. The flow passing through the filter element (outside to inside) must establish an exit flow path. This exit flow path is through the fuel filtering media from the outside, to the inside, and ultimately in an upward axial direction. It is important to configure the flow path and the various seals in order to isolate the dirty fuel from the fuel being filtered and to prevent the dirty fuel from bypassing the filtering element and exiting to the engine with the filtered fuel. Accordingly, one of the unique aspects of the present invention is the seal design used to establish a leak-free seal between the fuel flow exit apertures which are designed to receive the filtered fuel and the dirty fuel which can migrate below the filter element and flow upwardly toward the (clean) fuel flow exit apertures.
One embodiment of the present invention concerns a filter-housing assembly. The assembly includes a housing having a hollow interior and a cover that encloses the interior of the housing. The cover has an unfiltered fluid inlet channel and a concentric filtered fluid outlet channel defined therein. A filter cartridge is provided in the interior of the housing. The filter cartridge includes a filter media constructed and arranged to filter the fluid. The filter media has a central passage defined therein between first and second ends of the filter media. A first endplate is provided on the first end of the filter media, and the first endplate has a central opening aligned with the central passage. The first endplate has one or more peripheral openings defined therein around the central opening. A separate seal retainer attached to the first endplate, and the retainer has an outer body portion and a concentric inner body portion that extends from the outer body portion. The outer body portion has a first outwardly opening channel defined therein, and the inner body portion has a second outwardly opening channel defined therein. An outer seal is provided in the first channel, and the outer seal is constructed and arranged to seal the filter housing. An inner seal is provided in the second channel, and the inner seal is constructed and arranged to seal the inlet channel from the outlet channel of the cover.
Another embodiment concerns a filter cartridge for filtering fluid. The filter cartridge includes a filter media that is constructed and arranged to filter the fluid. The filter media has a central passage defined therein between first and second ends of the filter media. A first endplate is provided on the first end of the filter media, and the first endplate has a central opening aligned with the central passage. The first endplate has one or more peripheral openings defined therein around the central opening. A separate seal retainer is attached to the first endplate. The retainer has an outer body portion and a concentric inner body portion extending from the outer body portion. The outer body portion has a first outwardly opening channel, and the inner body portion has a second outwardly opening channel defined therein. An outer seal is provided in the first channel, and an inner seal provided in the second channel. A second endplate has a tube extending within the passage of the filter media. The tube has one or more fluid passage apertures defined at one end of the tube proximal the first endplate. The apertures and the first endplate define one or more fluid openings.
A further embodiment concerns a filter cartridge. The filter cartridge includes a cylindrical filter media constructed and arranged to filter fluid. The filter media has a central passage defined therein between first and second ends of the filter media. A first endplate is provided on the first end of the filter media. The first endplate has a central opening aligned with the central passage. The first endplate has one or more peripheral openings defined therein around the central opening. A separate seal retainer is attached to the first endplate. The retainer has an outer body portion and a concentric inner body portion that extends from the outer body portion. The outer body portion is constructed and arranged to retain an outer seal, and the inner body portion is constructed and arranged to retain an inner seal. A second endplate has a tube that extends from the second endplate within the central passage of the filter media. The tube has one or more fluid passage apertures defined at one end of the tube proximal the first endplate. The tube has an inside surface with an inwardly extending lip that extends from the inside surface. A center post gasket is coupled to the lip, and the center post gasket has a seal surface constructed and arranged to seal against a center post of a filter housing. The seal surface includes an upper conical surface portion, a lower conical surface portion, and a rounded surface portion provided between the upper and lower conical surface portions.
One object of the present invention is to provide an improved filter cartridge.
Related objects and advantages of the present invention will be apparent from the following description.